Some guys may be surprised to hear this, but bras are a pain in the butt to wash, and many of us put off the chore for as long as possible. (We wash everything else though, we swear.) That’s gross, but is it actually bad for you?

Isha Aran at Fusion sent her bra to a microbiologist to find out. The results, she says, were “both comforting and horrifying” because it really was full of germs—but they were mostly the harmless species you already have on your skin. Here’s what happens, according to Michael Schmidt, a microbiologist at the Medical University of South Carolina:

[With] daily wear for months—the garment will become soiled with the oils of the wearer that in turn will serve to support the growth of microbes from the skin, that have transferred to the fabric...If the skin of the wearer is unbroken, and they are healthy, the ‘new microbes/opportunists’ should not cause any problems…as long as the wearer has hygienic practices.

“Opportunists” are bacteria that don’t normally cause a problem, but that could cause infection if they got into an open wound, especially if your immune system isn’t working very well due to another illness. Aran’s bra did house some of these germs, including coagulase-negative staphylococcus.

Fortunately our friends at Jezebel have a complete bra washing guide, in case you’re feeling a sudden need. In the meantime, check out Aran’s article at the link below for more on what happens to unwashed bras.